Quinoline carboxylic acid

ABSTRACT

5-Amino-7-((3S,4S)-3-amino-4-methyl (or ethyl)-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylic acid or a pharmacologically acceptable salt thereof represented by the following formula wherein asymmetric carbon atoms marked with asterisks are in the S-configurations and R 1  represents methyl group or ethyl group; and an antibacterial agent comprising said compound as an active ingredient. ##STR1##

FIELD OF THE INVENTION

The present invention relates to5-amino-8-methyl-7-pyrrolidinylquinoline-3-carboxylic acid derivativesand pharmacologically acceptable salts thereof which are useful foractive ingredients of antibacterial agents, as well as to antibacterialagents comprising the substances as active ingredients.

BACKGROUND ART

Ciprofloxacin (The Merck Index 11th Edition, No.2315) is known as one ofquinolone-type synthetic antibacterial agents that have cyclopropylgroup at the 1-position of quinoline structure. A number of compoundswith modifications at 5, 7, and 8-positions of this compound have beensynthesized in order to improve antibacterial activity, physicochemicalproperties, e.g., water solubility, and safety of ciprofloxacin. Forexample, the Japanese Patent Unexamined Publication (KOKAI) No.(Sho)62-215572/1987 discloses the compound as set out below in which apiperazinyl group is introduced at the 7-position of the quinolinestructure that has amino group at the 5-position and methyl group at the8-position. However, a compound has not yet been known in which3-amino-4-methyl (or ethyl)-pyrrolidinyl group is introduced at the7-position of the quinoline structure having amino group at the5-position and methyl group at the 8-position. ##STR2##

Although the quinolone-type synthetic antibacterial agents so farreported have potent antibacterial activities, they have problems from aviewpoint of safety, for example, phototoxicity, induction ofchromosomal aberration, and induction of convulsion. These problems ofthe quinolone-type synthetic antibacterial agents are explained in eachof the following literatures: Quinolone Antimicrobial Agents, 2ndedition, Chapter 26, Ed. By D. C. Hooper and J. S. Wolfson, AmericanSociety for Microbiology, Washington D.C., 1993, p.489 (phototoxicity,induction of chromosomal aberration, induction of convulsion and other);Mutagenicity Test (Henigen-sei Shiken) 2(3), p.154, 1993 (chromosomalaberration and other); and Environ. Mol. Mutagen., 13, p.238, 1989(chromosomal aberration and other).

An object of the present invention is to provide quinolone-typesynthetic antibacterial agents having high antibacterial activity, andin addition, whose adverse reactions such as phototoxicity, induction ofchromosomal aberration, and induction of convulsion are reduced.

As for correlation between structures and adverse reactions of thequinolone-type synthetic antibacterial agents, the following generalpredictability has been noted in view of the state of the art: (A) as asubstituent at the 8-position of a quinoline structure, a somewhat bulkysubstituent such as a chlorine atom or methyl group is preferred from aviewpoint of antibacterial activity; however, a compound having achlorine atom at the 8-position has strong adverse reactions such asphototoxicity or induction of chromosomal aberration, and a compoundhaving methyl group exhibits strong adverse reactions such as inductionof chromosomal aberration; (B) amino group, halogen atoms, methyl groupand the like have been used as a substituent at the 5-position of aquinoline structure; however, these substituents decrease antibacterialactivity, or alternatively, increase adverse reactions such asphototoxicity or induction of chromosomal aberration; and (C)antibacterial activity is improved when one of 3-aminopyrrolidines isintroduced as a substituent at the 7-position of a quinoline structure;however, adverse reactions such as induction of chromosomal aberrationare increased.

The inventors of the present invention conducted various researches toachieve the foregoing object. As a result, they found that, contrary tothe aforementioned general predictability,1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acidderivatives, in which amino group at the 5-position, methyl group at the8-position, and 3-amino-4-methyl (or ethyl)-pyrrolidinyl group at the7-position are substituted together, have potent antibacterialactivities, and that the compounds are highly safe with reduced adversereactions such as phototoxicity, induction of chromosomal aberration,and induction of convulsion. The Japanese patent application No. (Hei)6-215213/1994 was filed on the basis of this invention.

The inventors of the present invention conducted further researches, andthey consequently found that, among compounds that fall within thecompounds of the aforementioned general formula, optically activecompounds each having the substituent in a specific stereostructure haveboth excellent antibacterial activities and remarkably high safeties.The present invention was achieved on the basis of these findings.

DISCLOSURE OF THE INVENTION

According to the first aspect of the present invention, there areprovided5-amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid, and5-amino-7-((3S,4S)-3-amino-4-ethyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid represented by the following formula (1) wherein the asymmetriccarbon atoms marked with asterisks are in the S-configurations, and R¹represents methyl group or ethyl group, and pharmacologically acceptablesalts thereof. Medicaments and antibacterial agents comprising theaforementioned compounds as active ingredients are also provided.##STR3##

As preferred embodiments according to the invention, there are provided5-amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid and a pharmacologically acceptable salt thereof, and a medicamentand an antibacterial agent comprising said compound as an activeingredient.

According to another aspect of the present invention, there are provided5-amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid derivatives and5-amino-7-((3S,4S)-3-amino-4-ethyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid derivatives represented by the following formula (II) wherein theasymmetric carbon atoms marked with asterisks are in theS-configurations, R¹ represents methyl group or ethyl group, R²represents a hydrogen atom, a lower alkyl group, or BF₂ group, and R³and R⁴ independently represent a hydrogen atom or an amino protectivegroup, with the proviso that R², R³, and R⁴ are not simultaneouslyhydrogen atoms. These compounds are useful as synthetic intermediatesfor the manufacture of the aforementioned compound (I). ##STR4##

BEST MODE FOR CARRYING OUT THE INVENTION

The compounds (I) of the present invention can be converted into salts,if desired, preferably into pharmacologically acceptable salts. Furtherconversions into compounds in the free form may be carried out bygenerating bases or acids from the resulting salts. As thepharmacologically acceptable salts, acid addition salts or alkaliaddition salts may be used. In addition, the compounds (I) of thepresent invention and salts thereof that may exist in any crystallineforms, as well as any hydrates of the compound (I) of the presentinvention and salts thereof fall within the scope of the presentinvention.

As the acid addition salts, for example, mineral acid salts such ashydrochlorides, hydrobromides, nitrates, sulfates, hydroiodides, orphosphates; and organic acid salts such as acetates, maleates,fumarates, citrates, oxalates, malates, methanesulfonates,p-toluenesulfonates, mandelates, 10-camphorsulfonates, tartrates,lactates, 5-oxotetrahydrofuran-2-carboxylates, or 2-hydroxygultaratesmay be used. As the alkali addition salts, for example, inorganic alkalisalts such as sodium salts, potassium salts, calcium salts, magnesiumsalts, or ammonium salts, or salts of organic bases such as ethanolamineor N,N-dialkylethanolamine may be used.

In the compounds (II) of the present invention, R² represents a hydrogenatom, a lower alkyl group, or BF₂. As the lower alkyl group, straight-or branched-chain alkyl groups having 1 to 6 carbon atoms, preferably 1to 4 carbon atoms. For example, methyl group, ethyl group, n-propylgroup, isopropyl group, n-butyl group, isobutyl group, sec-butyl group,or tert-butyl group may preferably be used.

As each of the amino protective groups represented by R³ and R⁴, anygroups may be used so far that they are substantially inert in areaction system in which the amino group should not be involved in thereaction, and that they can be readily cleaved under conditions of acertain deblocking reaction to regenerate the amino group. For example,lower alkanoyl groups, halogenated lower alkanoyl groups, arylcarbonylgroups, aryloxycarbonyl groups, aralkyloxycarbonyl groups, loweralkyloxycarbonyl groups, alkylsilyl groups, or aralkyl groups may beused.

Where these protective groups are used, an ordinary skilled artisan mayappropriately decide, depending on the sort of the protective group usedas R³, which of a protective group or a hydrogen atom should be appliedas R⁴. For example, where a lower alkanoyl group is used as R³, ahydrogen atom is generally used as R⁴. Where benzyl group is used as R³,an alkylsilyl group or other benzyl group can be introduced as R⁴. Whereboth of R³ and R⁴ are protective groups, examples include phthalimidegroup or maleimide group.

As the lower alkanoyl group, straight- or branched-chain alkanoyl groupshaving 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms may be used.For example, formyl group, acetyl group, propanoyl group, butyroylgroup, or trimethylacetyl group may preferably be used. As thehalogenated lower alkanoyl group, those may be used include theaforementioned alkanoyl group substituted with one or more halogen atomswhich may be the same or different. As the halogen atom, any one of afluorine atom, a chlorine atom, a bromine atom, or an iodine atom may beused. Preferred examples include fluoroacetyl group, difluoroacetylgroup, trifluoroacetyl group, chloroacetyl group, dichloroacetyl group,and trichloroacetyl group.

As aryl groups that constitute the arylcarbonyl group, aryloxycarbonylgroup, aralkyloxycarbonyl group, or aralkyl group, substituted ornon-substituted aryl groups having 6 to 10 carbon atoms, e.g., phenylgroup, p-methoxyphenyl group, p-chlorophenyl group, or naphthyl group,may be used. Benzoyl group or the like is preferable as the arylcarbonylgroup, and phenoxycarbonyl group or the like is preferred as thearyloxycarbonyl group. As the aralkyloxycarbonyl group, preferableexamples include benzyloxycarbonyl group, p-methoxybenzyloxycarbonylgroup or the like, and as the aralkyl group, preferable examples includebenzyl group, p-methoxybenzyl group or the like. As the loweralkyloxycarbonyl group, preferable examples include methoxycarbonylgroup, ethoxycarbonyl group, tert-butoxycarbonyl group or the like.Trimethylsilyl group or the like may be used as the alkylsilyl group.

Among them, compounds wherein R³ is a lower alkyloxycarbonyl group andR⁴ is a hydrogen atom are preferred, and compounds wherein R³ istert-butoxycarbonyl group and R⁴ is a hydrogen atom are particularlypreferred. Where the groups represented by R², R³, and R⁴ have one ormore asymmetric carbon atoms, the asymmetric carbon atom(s) may have anyconfiguration(s). In addition, among the compounds of the presentinvention represented by formula (II), where R² is a hydrogen atom, orthe amino group exhibit basicity depending on the sorts of R³ and R⁴,the compounds (II) may form acid addition salts or base addition salts.As the acid addition salts or base addition salts mentioned above, thepharmacologicallyacceptable acid addition salts or alkali addition saltsexemplified above may preferably be used.

The compounds (I) and (II) of the present invention can be prepared, forexample, according to the method disclosed in the specification of theJapanese Patent Application No. (Hei) 6-215213/1994.

More specifically, according to the first embodiment of the method forpreparation, the compounds represented by formula (I) can be prepared byreacting a 7-halogenoquinoline-3-carboxylic acid derivative representedby the following formula (III): ##STR5## wherein R² represents ahydrogen atom or a lower alkyl group, and X represents a halogen atom,preferably a fluorine atom or a chlorine atom, and most preferably afluorine atom, with a pyrrolidine derivative represented by thefollowing formula (IV): ##STR6## wherein each of R¹, R³, R⁴, and * hasthe same meaning as that defied above, in the presence or absence of abase in a solvent to obtain the compound (II), optionally followed bydeblocking of R³ and R⁴ and ester hydrolysis of R².

As for the solvents used for the reaction of the compound represented bythe general formula (III) with the compound represented by the generalformula (IV), any solvents may be used so far that they, per se, areinert in the reaction, and do not inhibit the reaction. For example,alcoholic solvents such as methanol, ethanol, n-propanol, isopropanol,or n-butanol; aprotic polar solvents such as acetonitrile,N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide,sulfolane, or hexamethylphosphoric triamide; aromatic hydrocarbonicsolvents such as benzene or toluene; organic basic solvents such aspyridine, picoline, lutidine, or collidine; or mixed solvents thereofmay be used.

Examples of the bases that are optionally used include, for example,triethylamine, N,N-diisopropylethylamine, 1,8-diazabicyclo5.4.0!-7-undecene, 1,2,2,6,6-pentamethylpiperidine, 1,4-diazabicyclo2.2.2!octane, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, and potassium hydrogen carbonate. Where organic bases such aspyridine are used as solvents, addition of a base may sometimes beunnecessary since the solvents, per se, can work as bases. The reactionmay be carried out at a temperature ranging from ice-cooling torefluxing temperature of a solvent.

Where R² is a lower alkyl group, the hydrolysis of the ester may becarried out according to a method that is known, per se, by using anacid or a base. Acids such as hydrochloric acid or sulfuric acid may beused for acidic hydrolysis, and alkalis such as sodium hydroxide orpotassium hydroxide may be used for alkaline hydrolysis. These acids oralkalis may used as aqueous solutions, or alternatively, they may beused as solutions in organic solvents such as methanol, ethanol,n-butanol, sec-butanol, or tert-butanol; or as solutions inwater-containing organic solvents. The reaction may be carried out at atemperature ranging from room temperature to refluxing temperature of asolvent.

The amino-deblocking reaction of R³ and R⁴ may be carried out byappropriate methods depending on the type of the protective group. Forexample, where R³ is a lower alkanoyl group or a halogenated loweralkanoyl group, the compound (I) can be prepared by treating thecompound (II) under a similar condition to that of the aforementionedhydrolysis reaction. Where ester-type groups such as tert-butoxycarbonylgroup are used as R³, deblocking reactions may be easily carried out bya treatment using an acid such as hydrochloric acid, hydrobromic acid,trifluoroacetic acid or the like without a solvent or in a solvent suchas acetic acid, ethyl acetate, dioxane, water, methanol, ethanol, or amixture thereof, optionally in the presence of a cation scavenger suchas anisole or thioanisole. The reaction may be carried out at atemperature ranging from ice-cooling to refluxing temperature of asolvent.

According to the second embodiment of the method for preparation, thecompound (I) can be prepared by reacting a boronic derivativerepresented by the following general formula (V): ##STR7## wherein X isthe same as that defined above, with the pyrrolidine derivativerepresented by the aforementioned general formula (IV) in a solvent inthe presence or absence of a base to prepare the compound (II),optionally followed by de-chelation of R² and deblocking of R³ and R⁴.The aforementioned de-chelation reactions may generally be carried outby a treatment with a protic polar solvent in the presence or absence ofa base.

In the method for preparation according to the aforementioned secondembodiment, as for the solvents used for the reaction of the compoundrepresented by the general formula (V) with the compound represented bythe general formula (IV), any solvents may be used so far that they, perse, are inert in the reaction, and do not inhibit the reaction. Forexample, alcoholic solvents such as methanol, ethanol, n-propanol,isopropanol, or n-butanol; aprotic polar solvents such as acetonitrile,N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, orhexamethylphosphoric triamide; aromatic hydrocarbonic solvents such asbenzene or toluene; organic basic solvents such as pyridine, picoline,lutidine, or collidine; halogenated hydrocarbonic solvents such asdichloromethane, 1,2-dichloroethane, or chloroform: or mixed solventsthereof may be used.

Examples of the bases that are optionally used include, for example,triethylamine, N,N-diisopropylethylamine, 1,8-diazabicyclo5.4.0!-7-undecene, 1,2,2,6,6-pentamethylpiperidine, 1,4-diazabicyclo2.2.2!octane, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, and potassium hydrogen carbonate. Where organic bases such aspyridine are used as solvents, addition of a base may sometimes beunnecessary since the solvents, per se, can work as bases. The reactionmay be carried out at a temperature ranging from ice-cooling torefluxing temperature of a solvent.

As the protic polar solvents used in the de-chelation reaction, forexample, alcoholic solvents such as methanol, ethanol, n-propanol,isopropanol, or n-butanol; water: or mixed solvents thereof may be used.Mixed solvents may also be used in which these solvents are added withaprotic solvents such as acetonitrile, N,N-dimethylformamide,N-methyl-2-pyrrolidone, dimethylsulfoxide, hexamethylphosphorictriamide, benzene, toluene, pyridine, picoline, lutidine, collidine,dichloromethane, 1,2-dichloroethane, or chloroform.

Examples of the bases that are optionally used in the de-chelationreaction include, for example, triethylamine, N,N-diisopropylethylamine,1,8-diazabicyclo- 5.4.0!-7-undecene, 1,2,2,6,6-pentamethylpiperidine,1,4-diazabicyclo 2.2.2!octane, sodium carbonate, potassium carbonate,sodium hydrogen carbonate, and potassium hydrogen carbonate. Thereaction may be carried out at a temperature ranging from ice-cooling torefluxing temperature of a solvent.

Among the compounds used as starting materials for these methods ofpreparation, the compounds (III) and (V) can be prepared, for example,according to the method shown in the scheme set out below. In thescheme, the compound (VII) is known, i.e., disclosed in the JapanesePatent Unexamined Publication (KOKAI) No.(Sho)62-215572/1987. The symbol"X" has the same meaning as that defined above, and the symbol "Y"represents a halogen atom. ##STR8##

The reactions in the scheme will be explained. In the step 1 wherein3-methyl-2,4,5-trihalogenobenzoic acid (VII) is subjected to nitrationto obtain the compound (VIII), nitric acid, niter, ammonium nitrate orthe like may be used as the agent for nitration. Sulfuric acid, aceticacid, acetic anhydride, trifluoroacetic anhydride, fuming nitric acid orthe like may be used as a solvent. The resulting compound (VIII) istreated with a chlorinating agent such as thionyl chloride, oxalylchloride or the like according to the step 2 to convert into the acidchloride (IX). Where a solvent is used, solvents such as chloroform,methylene chloride, 1,2-dichloroethane or the like may be used. Thereaction may optionally be carried out in the presence ofN,N-dimethylformamide.

The compound (X) is obtained by condensing diethylethoxy-magnesium-malonate, that is prepared from ethanol, diethylmalonate, and magnesium, with the above compound (IX) in a solvent suchas benzene or toluene (step 3), and then the compound (X) is heated withwater in the presence of an acid such as hydrochloric acid, sulfuricacid, p-toluenesulfonic acid or the like to obtain the compound (XI) bysimultaneous hydrolysis and decarboxylation (step 4). After then, thecompound (XI) is allowed to react with ethyl orthoformate in aceticanhydride to obtain the compound (XII) (step 5). This reaction mayoptionally be carried out in the presence of a Lewis acid such as zincchloride.

The resulting compound (XII) is allowed to react with cyclopropylaminein a solvent to convert into the compound (XIII) (step 6). As thesolvents, any solvents may be used so far that they, per se, are inertin the reaction and do not inhibit the reaction. For example, alcoholicsolvents such as methanol or ethanol; halogenated hydrocarbonic solventssuch as chloroform or 1,2-dichloroethane; aromatic hydrocarbonicsolvents such as benzene or toluene; or aprotic polar solvents such asacetonitrile or N,N-dimethylformamide.

The compound (XIII) is then treated with a base in a solvent to obtainthe compound (XIV) by a ring closure (step 7). Potassium carbonate,sodium hydride, potassium tert-butoxide or the like may be used as thebase. As the solvents, ethereal solvents such as dioxane ortetrahydrofuran; or aprotic polar solvents such as acetonitrile, orN,N-dimethylformamide may be used. A catalyst may optionally be used inthis reaction. For example, catalysts such as crown ethers,tetrabutylammonium bromide, benzyltriethylammonium bromide or the likemay be employed.

The compound (III-a) can be obtained by subjecting the resultingcompound (XIV) to catalytic hydrogenation using a catalyst such as Raneynickel, palladium carbon, platinum oxide or the like, or alternatively,to reduction under an acidic condition by using a metal such as iron,tin, zinc or the like (step 9). Acetic acid, water, methanol, ethanol,N,N-dimethylformamide or the like may be used as a solvent. Acids suchas hydrochloric acid, acetic acid, hydrobromic acid or the like may beused for the reduction using a metal. The compound (III-b) can beobtained by hydrolyzing the compound (III-a) in a solvent such as water,acetic acid, alcohols, water-containing alcohols or the like under anacidic condition such as with hydrochloric acid, acetic acid,hydrobromic acid or the like. Then, the compound (V) can be obtained byreacting the compound (III-b) with boron trifluoride diethyl ethercomplex in a solvent such as ether, acetone, methylisobutylketone or thelike. Each of the reactions has been explained along with the scheme.Further specific methods for preparation will be explained in Examples.

Among the pyrrolidine derivatives represented by the general formula(IV), compounds wherein R⁴ is a hydrogen atom can be prepared accordingto the method shown in the scheme set out below. In the scheme, thecompound (XV) is a known compound, i.e., disclosed in the JapanesePatent Publication for International Application (KOHYO) No. (Hei)6-508136/1994. R¹ and R³ are the same as those defined above, and thesymbol "Z" represents a leaving group such as a halogen atom, triflateor the like. ##STR9##

The reactions in the scheme will be explained. Step 1 comprises the stepof treating the compound (XV) with an alkylating agent in a solvent inthe presence of a base to obtain the compound (XVI). As the base, forexample, lithium diisopropylamide (LDA), lithiumbis(trimethylsilyl)amide or the like may preferably be used. As thesolvent, for example, ethereal solvents such as ether, diisopropylether, tetrahydrofuran, 1,2-dimethoxyethane or the like may preferablybe used. The reaction may be carried out at a temperature ranging from-75° C. to room temperature.

Step 2 comprises the step of treating the compound (XVI) with a reducingagent in a solvent to obtain the compound (XVII) whose amino group isprotected. As the reducing agent, for example, lithium aluminum hydride,diisobutylaluminum hydride, bis(2-methoxyethoxy)aluminum hydride or thelike may preferably be used. As the solvent, for example, etherealsolvents such as ether, diisopropyl ether, tetrahydrofuran or the likemay preferably be used. The reaction may be carried out at a temperatureranging from -40° C. to a refluxing temperature of a solvent.

Step 3 comprises the step of hydrogenolyzing the compound (XVII) in asolvent in the presence of a catalyst to obtain the compound (XVIII)whose amino group is deblocked. As the catalyst, for example, catalystsfor hydrogenation such as Raney nickel, palladium carbon, platinum oxideor the like may preferably be used. The sorts of the solvents are notparticularly limited so far that they do not inhibit the reaction. Forexample, alcoholic solvents such as methanol, ethanol, propanol, orbutanol; water-containing alcoholic solvents; aromatic hydrocarbonicsolvents such as benzene, toluene, or xylene; aprotic polar solventssuch as acetonitrile, N,N-dimethylformamide, or dimethylsulfoxide;ester-type solvents such as methyl acetate or ethyl acetate may be used.As the source of hydrogen, cyclohexadiene, formic acid, ammonium formateor the like as well as hydrogen gas may be used.

Step 4 comprises the step of treating the compound (XVIII) with (R³)₂ Oor R³ Z in a solvent in the presence of absence of a base to obtain thecompound (XIX) whose amino group is protected. As the base, for example,organic bases such as triethylamine, N,N-diisopropylethylamine,1,8-diazabicyclo 5.4.0!-7-undecene, or pyridine; or inorganic bases suchas sodium carbonate, potassium carbonate, sodium hydrogen carbonate, orpotassium hydrogen carbonate may be used. As the solvent, for example,alcoholic solvents such as methanol, ethanol, propanol, or butanol;ethereal solvents such as ether, diisopropyl ether, tetrahydrofuran, or1,2-dimethoxyethane; aprotic polar solvents such as acetonitrile,N,N-dimethylformamide, or dimethylsulfoxide; ester-type solvents such asmethyl acetate or ethyl acetate; halogen-containing hydrocarbonicsolvents such as methylene chloride, chloroform, or 1,2-dichloroethanemay be used. The reaction may be carried out at a temperature rangingfrom ice-cooling to a refluxing temperature of a solvent.

Step 5 comprises the step of condensing the compound (XIX) withmethanesulfonyl chloride in a solvent in the presence or absence of abase to obtain the compound (XX) in which each of the two hydroxylgroups is sulfonylated. As the base, for example, organic bases such astriethylamine, N,N-diisopropylethylamine, 1,8-diazabicyclo5.4.0!-7-undecene, or pyridine; or inorganic bases such as sodiumcarbonate, potassium carbonate, sodium hydrogen carbonate, or potassiumhydrogen carbonate may be used. The sorts of the solvents are notparticularly limited so far that they do not inhibit the reaction. Forexample, aprotic polar solvents such as acetonitrile,N,N-dimethylformamide, or dimethylsulfoxide; ester-type solvents such asmethyl acetate or ethyl acetate; halogen-containing hydrocarbonicsolvents such as methylene chloride, chloroform, or 1,2-dichloroethane;aromatic hydrocarbonic solvents such as benzene, toluene, or xylene;ethereal solvents such as ether, diisopropyl ether, tetrahydrofuran, or1,4-dioxane may be used. The reaction may be carried out at atemperature ranging from ice-cooling to a refluxing temperature of asolvent.

Step 6 comprises the step of reacting the compound (XX) with benzylaminein the presence or absence of a base in a solvent or without a solventto prepare a (3S,4S)-3-amino-4-methyl (or ethyl)-pyrrolidine derivative(XXI) which is protected at the 1-position. As the base, for example,organic bases such as triethylamine, N,N-diisopropylethylamine,1,8-diazabicyclo 5.4.0!-7-undecene, or pyridine; or inorganic bases suchas sodium carbonate, potassium carbonate, sodium hydrogen carbonate, orpotassium hydrogen carbonate may be used. The sorts of the solvents arenot particularly limited so far that they do not inhibit the reaction.For example, aromatic hydrocarbonic solvents such as benzene, toluene,or xylene; aprotic polar solvents such as acetonitrile,N,N-dimethylformamide, or dimethylsulfoxide; ester-type solvents such asmethyl acetate or ethyl acetate; halogen-containing hydrocarbonicsolvents such as methylene chloride, chloroform, or 1,2-dichloroethane;ethereal solvents such as ether, tetrahydrofuran, 1,4-dioxane, ordiisopropyl ether may be used. The reaction may be carried out at atemperature ranging from ice-cooling to 200° C.

Step 7 comprises the step of hydrogenolyzing the(3S,4S)-3-amino-4-methyl (or ethyl)-pyrrolidine derivative (XXI) whichis protected at the 1-position in a solvent in the presence of acatalyst to prepare a (3S,4S)-3-amino-4-methyl (or ethyl)-pyrrolidinederivative (IV) whose 1-position is deblocked. As the catalyst, forexample, catalysts for hydrogenation such as Raney nickel, palladiumcarbon, platinum oxide or the like may preferably be used. The sorts ofthe solvents are not particularly limited so far that they do notinhibit the reaction. For example, alcoholic solvents such as methanol,ethanol, propanol, or butanol; water-containing alcoholic solvents;aromatic hydrocarbonic solvents such as benzene, toluene, or xylene;aprotic polar solvents such as acetonitrile, N,N-dimethylformamide, ordimethylsulfoxide; ester-type solvents such as methyl acetate or ethylacetate may be used. As the source of hydrogen, cyclohexadiene, formicacid, ammonium formate or the like as well as hydrogen gas may be used.

Each of the reactions has been explained along with the scheme. Furtherspecific methods for preparation will be explained in Examples.

The medicament, which comprises, as an active ingredient, at least onesubstance selected from the group consisting of the aforementionedcompound (I):5-amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid,5-amino-7-((3S,4S)-3-amino-4-ethyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid, and pharmacologically acceptable salts thereof, is useful as anantibacterial agent. The antibacterial agents mentioned above maygenerally be administered for therapeutic and/or preventive treatmentsof infectious diseases of human or mammals as orally availablepreparations such as capsules, tablets, fine granules, granules,powders, syrups or the like, or alternatively, as injections,suppositories, eye drops, ophthalmic ointments, ear solutions, ortopical preparations.

These preparations may be manufactured according to ordinary methods byusing pharmacologically and pharmaceutically acceptable additives. Forthe manufactures of oral preparations and suppositories, pharmaceuticaladditives such as, for example, excipients such as lactose, D-mannitol,corn starch, or crystalline cellulose; disintegrators such ascarboxymethylcellulose or carboxymethylcellulose calcium; binders suchas hydroxypropylcellulose, hydroxypropylmethylcellulose, orpolyvinylpyrrolidone; lubricants such as magnesium stearate or talc;coating materials such as hydroxypropylmethylcellulose, sucrose, ortitanium oxide; plasticizer such as polyethyleneglycol; base materialssuch as polyethyleneglycol or hard fat may be used.

For the manufactures of injections, eye drops, or ear solutions,pharmaceutical additives such as solubilizers or solubilizing agents,which are ingredients for aqueous formulations or formulations to bedissolved before use, such as water for injection, physiological saline,or propyleneglycol; pH modifier such as inorganic or organic acids orbases; isotonicities such as sodium chloride, glucose, or glycerin; orstabilizers may be used. In addition, for the manufactures of ophthalmicointments or topical preparations, pharmaceutical additives suitable asbase materials for ointments, creams, or patches such as white softparaffin, macrogol, glycerol, liquid paraffin, cotton sheet may be used.

Where the aforementioned antibacterial agent is administered fortherapeutic or preventive treatment of a human infectious disease, anoral dose of about 10 to 1,000 mg, or parenteral dose of 1 to 500 mg perday for an adult may be administered once a day or several times asdivided dosages. However, it is desirable that the dosage should beappropriately increased or decreased depending on the purpose oftherapeutic or preventive treatment, focus of infection or the sort ofpathogenic bacteria, the age of a patient, symptoms and the like.

EXAMPLE

The present invention will be explained more specifically by Examples.However, the scope of the present invention is not limited to theseexamples.

Example 1 Manufacture of the compound (I) of the present invention

2,4,5-Trifluoro-3-methyl-6-nitrobenzoic acid

To a mixture of acids containing 370 ml of conc. sulfuric acid and 61.2ml of 70% nitric acid, 36.6 g of 2,4,5-trifluoro-3-methylbenzoic acidwas added portionwise at the inner temperature of 55°-70° C. withstirring, and then stirring was continued for 2 hours at roomtemperature. The reaction mixture was poured into ice and extracted withisopropyl ether. The extract was washed with brine, and then dried andconcentrated to give 30.6 g of yellow crystals.

NMR spectrum δ(CD₃ OD) ppm: 2.29 (3H, t, J=2 Hz)

Diethyl (2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)malonate

A suspension containing 27.0 g of2,4,5-trifluoro-3-methyl-6-nitrobenzoic acid, 19.5 ml of oxalylchloride, 270 ml of methylene chloride, and a few drops ofN,N-dimethylformamide was stirred at room temperature for 2 hours. Thereaction mixture was concentrated under reduced pressure to give2,4,5-trifluoro-3-methyl-6-nitrobenzoyl chloride. Separately, a fewdrops of carbon tetrachloride was added to a suspension of 3.08 g ofmagnesium in 6.4 ml of absolute ethanol, and then a solution of 19.2 mlof diethyl malonate in 12 ml of absolute ethanol was added dropwise tothe suspension under heating at 50° C., and the mixture was stirred atthe same temperature for 1.5 hours. The reaction mixture wasconcentrated under reduced pressure, and then, toluene was added todissolve the residue and the solution was again concentrated. To asolution of the residue in 30 ml of toluene, a solution of2,4,5-trifluoro-3-methyl-6-nitrobenzoyl chloride in 30 ml of toluene wasadded dropwise with stirring under ice cooling, and then stirring wascontinued for 2 hours at room temperature. The reaction mixture wasadded with 100 ml of 5% sulfuric acid, and was then extracted withdiethyl ether. The extract was washed with brine, and then dried andconcentrated to give 47.3 of brown oil.

NMR spectrum δ(CDCl₃) ppm: 1.12 (3H, t, J=7.5 Hz), 1.38 (3H, t, J=7.5Hz), 2.33 (3H, t, J=2 Hz), 3.36, 14.18 (total 1H, each s), 4.07 (2H, q,J=7.5 Hz), 4.38 (2H, q, J=7.5 Hz)

Ethyl (2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)acetate

A mixture of 45.3 g of diethyl(2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)malonate, 30 mg ofp-toluenesulfonic acid, and 120 ml of water was heated under reflux for50 minutes. After cooling, the reaction mixture was extracted withdiethyl ether, and the extract was washed with brine, and then dried andconcentrated to give 34.2 g of brown oil.

NMR spectrum δ(CDCl₃) ppm: 1.26, 1.34 (total 3H, each t, J=7 Hz), 2.33,2.35 (total 3H, each t, J=2.5 Hz), 3.91, 5.48, 12.34 (total 2H, each s),4.20, 4.28 (total 2H, each q, J=7 Hz).

Ethyl3-cyclopropylamino-2-(2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)acrylate

A mixture of 31.9 g of ethyl(2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)acetate, 26.2 ml of ethylorthoformate and 23.8 ml of acetic anhydride was heated under reflux for1 hour. The reaction mixture was concentrated under reduced pressure togive 46.2 g of ethyl 3-ethoxy-2-(2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)acrylate as brown oil. To a solution of 45.4 g ofthe above compound in 328 ml of ethanol, 9.6 ml of cyclopropylamine wasadded dropwise with stirring under ice cooling, and then stirring wascontinued for 30 minutes at room temperature. The reaction mixture wasconcentrated under reduced pressure, and the residue was purified bycolumn chromatography (silica gel, n-hexane-methylene chloride (1:1)) togive 28.8 g of yellow crystals. The crystals were recrystallized fromisopropyl ether to give yellow needles, m.p. 115°-115.5° C.

    ______________________________________    Analysis for C.sub.16 H.sub.15 F.sub.3 N.sub.2 O.sub.5    ______________________________________    Calculated %               C, 51.62     H, 4.06 N, 7.52    Found %    C, 51.57     H, 3.92 N, 7.53    ______________________________________

Ethyl1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-5-nitro-4-oxoquinoline-3-carboxylate

To a solution of 27.1 g of ethyl3-cyclopropylamino-2-(2,4,5-trifluoro-3-methyl-6-nitrobenzoyl)acrylatein 270 ml of dioxane, 3.2 g of 60% sodium hydride was added, and thenstirring was continued for 1 hour at room temperature. Water (300 ml)was added to the reaction mixture, and then the crystals precipitatedwere collected by filtration to obtain 19.5 g of colorless crystals. Thecrystals were. recrystallized from N,N-dimethylformamide to colorlessneedles, m.p. 260°-263° C.

    ______________________________________    Analysis for C.sub.16 H.sub.14 F.sub.2 N.sub.2 O.sub.5    ______________________________________    Calculated %               C, 54.55     H, 4.01 N, 7.95    Found %    C, 54.51     H, 4.00 N, 7.90    ______________________________________

Ethyl5-amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylate

A suspension containing 18.5 g of ethyl1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-5-nitro-4-oxoquinoline-3-carboxylate,10 ml of Raney nickel, and 300 ml of acetic acid was hydrogenated atroom temperature for 1.5 hours under atmospheric pressure. The catalystwas filtered off and the filtrate was concentrated. The resultingresidue was added with 150 ml of 10% aqueous potassium carbonate, andthen the mixture was extracted with methylene chloride. The organiclayer was dried and concentrated to give 14.8 g of pale yellow crystals.The crystals were recrystallized from acetonitrile to give pale yellowneedles, m.p. 182.5°-185.5° C.

    ______________________________________    Analysis for C.sub.16 H.sub.16 F.sub.2 N.sub.2 O.sub.3    ______________________________________    Calculated %               C, 59.62     H, 5.00 N, 8.69    Found %    C, 59.74     H, 5.08 N, 8.60    ______________________________________

5-Amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxlicacid

A mixture of 14.8 g of ethyl5-amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylate,150 ml of 90% acetic acid, and 37.2 ml of conc. hydrochloric acid washeated under reflux for 2 hours. The crystals precipitated werecollected by filtration and washed with water to give 11.8 g of yellowcrystals. The crystals were recrystallized from N,N-dimethylformamide togive yellow crystals, m.p. 290.5° C. (decomp.).

    ______________________________________    Analysis for C.sub.14 H.sub.12 F.sub.2 N.sub.2 O.sub.3    ______________________________________    Calculated %               C, 57.15     H, 4.11 N, 9.52    Found %    C, 57.10     H, 4.03 N, 9.53    ______________________________________

5-Amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylate-O³,O⁴!difluoroboron(5-Amino-1-cycloprolpyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid Bf₂ chelate)

A mixture of 5.00 g of5-amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid, 3.13 ml of boron trifluoride diethyletherate, and 75 ml of methylisobutyl ketone was heated under reflux for 1 hour. After cooling, thecrystals precipitated were collected by filtration and washed withdiethyl ether to give 5.38 g of yellow crystals.

NMR spectrum δ(DMSO-d₆) ppm: 1.08-1.15 (2H, m), 1.21-1.30 (2H, m), 2.67(3H, d, J=2.5 Hz), 4.52-4.59 (1H, m), 7.28 (2H, br-s), 9.10 (1H, s)

Dimethyl (2S,3R)-N-benzyl-3-methyl-N-(9-phenylfluoren-9-yl)aspartate

A solution of 1.66M of n-butyl lithium in 1966 ml of n-hexane was addeddropwise with stirring to a solution of 608 ml of hexamethyldisilazanein 3.2 L of tetrahydrofuran at -10° C. under nitrogen atmosphere, andthen stirring was continued at from -8° to 4° C. for 30 minutes. Asolution of 942 g of dimethyl(2S)-N-benzyl-N-(9-phenylfluoren-9-yl)aspartate in 3.2 L oftetrahydrofuran was added dropwise to the above reaction solution whilethe temperature was kept in the range of from -28° to -23° C., and thenthe stirring was continued at from -26° to 24° C. for 30 minutes. Afterthe mixture was cooled at from -65° to -64° C., the mixture was addeddropwise with 143 ml of methyl iodide and then stirred at from -73° to-65° C. for 1.5 hours, and stirring was further continued for 1 hour atfrom -30° to -21° C. Saturated aqueous ammonium chloride (3.8 L) wasadded to the reaction mixture, and the mixture was stirred for 15minutes under ice cooling and then layers were separated. The aqueouslayer was extracted with ethyl acetate, and the extract was combinedwith the organic layer previously obtained and washed with brine. Theextract was dried over sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was washed with methanol to obtain880 g of colorless crystals. The crystals were recrystallized frommethanol to give the colorless plates, m.p. 153°-155° C.

    ______________________________________    Analysis for C.sub.33 H.sub.31 NO.sub.4    ______________________________________    Calculated %               C, 78.39     H, 6.18 N, 2.77    Found %    C, 78.41     H, 6.15 N, 2.75    ______________________________________

Specific rotation α!_(D) ²⁰ -344.5° (c=1, CHCl₃)

The following compound was obtained in a similar manner.

Dimethyl (2S,3R)-N-benzyl-3-ethyl-N-(9-phenylfluoren-9-yl)aspartate

Appearance: colorless plates (MeOH)

m.p.: 162.5°-163.5° C.

    ______________________________________    Analysis for C.sub.34 H.sub.33 NO.sub.4    ______________________________________    Calculated %               C, 78.59     H, 6.40 N, 2.70    Found %    C, 78.50     H, 6.48 N, 2.57    ______________________________________

Specific rotation α!_(D) ²⁰ -331.8° (c=1, CHCl₃)

(2S,3R-)-2-N-Benzyl-N-(9-phenylfluoren-9-yl)!amino-3-methylbutane-1,4-diol

A suspension of 63 g of lithium aluminum hydride in 3.0 L of anhydroustetrahydrofuran was ice cooled, and a solution of 560 g of dimethyl(2S,3R)-N-benzyl-3-methyl-N-(9-phenylfluoren-9-yl)aspartate in 1.8 L ofanhydrous tetrahydrofuran was added dropwise to the above suspensionunder nitrogen atmosphere. After the mixture was stirred at roomtemperature for 30 minutes, 300 ml of water and 110 ml of 15% aqueoussodium hydroxide were added successively to the mixture under icecooling. Stirring was continued for 2 hours at room temperature, andthen the insoluble substances were removed by filtration. The insolublesubstances were washed with 1 L of tetrahydrofuran, and the filtrate andwashings were combined and then concentrated under reduced pressure. Theresidue was dissolved in ethyl acetate, and the solution was dried oversodium sulfate, and then, the solvent was evaporated under reducedpressure to obtain 544 g of colorless viscous oil. This product wassuitable for use in the next step without further purification. A partof the product was purified by column chromatography (silica gel, ethylacetate:n-hexane=1:2) to give colorless viscous oil.

IR spectrum ν(liq) cm⁻¹ : 3324 NMR spectrum δ(CDCl₃) ppm: 0.54 (3H, d,J=7 Hz), 1.50-1.60 (1H, m), 2.58-2.64 (1H, m), 2.84-2.93 (1H, m),3.02-3.10 (1H, m), 3.12-3.19 (1H, m), 3.22-3.29 (1H, m), 4.18 (1H, d,J=15.5 Hz), 4.29 (1H, d, J=15.5 Hz), 7.17-7.75 (18H, m) Specificrotation α!_(D) ²⁰ +106.7° (c=1, CHCl₃)

The following compound was obtained in a similar manner.

(2S,3R)-2-N-Benzyl-N-(9-phenylfluoren-9-yl)!amino-3-ethylbutane-1,4-diol

Appearance: colorless oil

IR spectrum ν(liq) cm⁻¹ : 3292 NMR spectrum δ(CDCl₃) ppm: 0.64 (3H, t,J=7.5 Hz), 0.81-1.02 (2H, m), 1.29-1.38 (1H, m), 1.81 (2H, br-s),2.76-2.87 (2H, m), 3.08-3.17 (1H, m), 3.24-3.35 (2H, m), 4.09 (1H, d,J=15 Hz), 4.26 (1H, d, J=15 Hz), 7.16-7.77(18H, m) Specific rotationα!_(D) ²⁰ +158.90 (c=1, CHCl₃)

(2S,3R)-2-Amino-3-methylbutane-1,4-diol

A mixture of 60 g of (2S,3R)-2-N-benzyl-N-(9-phenylfluoren-9-yl)!amino-3-methylbutane-1,4-diol, 6.0 gof 20% palladium hydroxide on charcoal, and 500 ml of methanol washydrogenated in an autoclave under 5 kgf/cm² hydrogen pressure at 40° C.for 2 hours. The catalyst was removed by filtration and the filtrate wasconcentrated under reduced pressure. The residue was added withisopropylalcohol and insoluble substances were removed by filtration.The filtrate was concentrated under reduced pressure to give 16.7 g ofcolorless viscous oil.

IR spectrum ν(liq) cm⁻¹ : 3360 NMR spectrum δ(CDCl₃) ppm: 0.90 (3H, d,J=7.5 Hz), 1.65-1.76 (1H, m), 2.60-3.00 (5H, m), 3.50-3.61 (2H, m),3.64-3.70 (2H, m)

The following compound was obtained in a similar manner.

(2S,3R)-2-Amino-3-ethylbutane-1,4-diol

Appearance: yellow oil

IR spectrum ν(liq) cm⁻¹ : 3360 NMR spectrum δ(CDCl₃) ppm: 0.95 (3H, t,J=7.5 Hz), 1.29-1.49 (3H, m), 2.41 (4H, br-s), 2.95-3.05 (1H, m),3.57-3.83 (4H, m)

(2S,3R)-2-(tert-Butoxycarbonyl)amino-3-methylbutane-1,4-diol

A solution of 234 g of di-tert-butyldicarbonate in 140 ml ofisopropylalcohol was added dropwise to a solution of 146 g of(2S,3R)-2-amino-3-methylbutane-1,4-diol in 500 ml of isopropylalcohol atroom temperature with stirring. After stirring was continued at roomtemperature for 30 minutes, the solvent was evaporated under reducedpressure to give 260 g of pale yellow viscous oil. This product wassuitable for use in the next step without further purification. A partof the product was purified by column chromatography (silica gel,methylene chloride:ethyl acetate=1:1) to give colorless viscous oil.

IR spectrum ν(liq) cm⁻¹ : 3352, 1690 NMR spectrum δ(CDCl₃) ppm: 1.03(3H, d, J=7 Hz), 1.45 (9H, s), 1.75-1.90 (1H, m), 2.72 (1H, br-s), 3.17(1H, br-s), 3.42-3.80 (5H, m), 5.23 (1H, br-s) Specific rotation α!_(D)²⁰ -10.4° (c=1, CHCl₃)

The following compound was obtained in a similar manner.

(2S,3R)-2-(tert-Butoxycarbonyl)amino-3-ethylbutane-1,4-diol

Appearance: colorless oil.

IR spectrum ν(liq) cm⁻¹ : 3384, 1692 NMR spectrum δ(CDCl₃) ppm: 0.98(3H, t, J=7.5 Hz), 1.38-1.60 (3H, m), 1.45 (9H, s), 2.77 (1H, br-s),2.84 (1H, br-s), 3.60-3.80 (5H, m), 5.28-5.35 (1H, m) Specific rotationα!_(D) ²⁰ -0.4° (c=1, CHCl₃)

(2S,3R)-2-(tert-Butoxycarbonyl)amino-1,4-bis(methanesulfonyloxyy-3-methylbutane

A solution of 249 g of(2S,3R)-2-(tert-butoxycarbonyl)amino-3-methylbutane-1,4-diol and 34 mlof triethylamine in 1,600 ml of methylene chloride was ice cooled, andthe solution was added dropwise with methanesulfonyl chloride (174 ml)with stirring. After stirring was continued for 30 minutes at roomtemperature, the mixture was washed twice with water. The organic layerwas dried over sodium sulfate and the solvent was evaporated underreduced pressure. The residue was washed with isopropyl ether to give341 g of pale brown crystals.

IR spectrum ν(KBr) cm⁻¹ : 3336, 1676 NMR spectrum δ(CDCl₃) ppm: 1.13(3H, d, J=7 Hz), 1.45 (9H, s), 2.10-2.22 (1H, m), 3.04 (3H, s), 3.06(3H, s), 3.81-3.93 (1H, m), 4.15-4.26 (2H, m), 4.26-4.40 (2H, m), 4.85(1H, br-s) Specific rotation α!_(D) ²⁰ -26.0° (c=1, CHCl₃)

The following compound was obtained in a similar manner.

(2S,3R)-2-(tert-Butoxycarbonyl)amino-1,4-bis(methanesulfonyloxy)-3-ethylbutane

Appearance: pale brown crystals

m.p.: 75.5°-76.5° C. (decomp.) IR spectrum ν(KBr) cm⁻¹ : 3380, 1692 NMRspectrum δ(CHCl₃) ppm: 1.01 (3H, t, J=7.5 Hz), 1.38-1.68 (2H, m), 1.45(9H,s), 1.90-2.00 (1H, m), 3.047 (3H, s), 3.053 (3H, s), 4.00-4.09 (1H,m), 4.28-4.38 (4H, m), 4.80-4.91 (1H, m) Specific rotation α!_(D) ²⁰-11.1° (c=1, CHCl₃)

(3S,4S)-1-Benzyl-3-(tert-butoxycarbonyl)amino-4-methylpyrrolidine

Benzylamine (290 ml) was stirred at room temperature and then addedportionwise with(2S,3R)-2-(tert-butoxycarbonyl)amino-1,4-bis(methanesulfonyloxy)-3-methylbutane(100 g). The mixture was stirred at room temperature for 24 hours, andthen poured into 600 ml of ice-water and stirring was continued for 30minutes. The crystals precipitated were collected by suction filtrationto give 45.1 g of pale brown crystals. The crystals were recrystallizedfrom isopropyl ether to give colorless needles, m.p. 100°-102° C.

Specific rotation α!_(D) ²⁰ +31.10 (c=1, CHCl₃)

The following compound was obtained in a similar manner.(3S,4S)-1-Benzyl-3-(tert-butoxycarbonyl)amino-4-ethylpyrrolidine

Appearance: colorless needles (n-Hexane)

m.p. :97°-98.5° C.

    ______________________________________    Analysis for C.sub.18 H.sub.28 N.sub.2 O.sub.2    ______________________________________    Calculated %               C, 71.02     H, 9.27 N, 9.20    Found %    C, 71.02     H, 9.55 N, 8.93    ______________________________________

Specific rotation α!_(D) ²⁰ +31.9° (c=1, CHCl₃)

(3S,4S)-3-(tert-Butoxycarbonyl)amino-4-methylpyrrolidine

A mixture of 60.0 g of(3S,4S)-1-benzyl-3-(tert-butoxycarbonyl)amino-4-methylpyrrolidine, 6.00g of 5% palladium on charcoal, and 500 ml of methanol was hydrogenatedin an autoclave under 5 kgf/cm² hydrogen pressure at 40° C. for 3 hours.The catalyst was removed by filtration, and then the filtrate wasconcentrated under reduced pressure. The product was recrystallized fromn-hexane to give 38.0 g of colorless needles, m.p. 83°-85° C.

NMR spectrum δ(CDCl₃) ppm: 0.97 (3H, d, J=7 Hz), 1.45 (9H, s), 2.20-2.30(1H, m), 2.44-2.53 (1H, m), 2.70 (1H, dd, J=11.5, 4.5 Hz), 3.15 (1H, dd,J=11, 7.5 Hz), 3.20-3.30 (1H, m), 4.05-4.20 (1H, m), 4.62 (1H, br-s)

    ______________________________________    High resolution mass spectrum for C.sub.10 H.sub.21 N.sub.2 O.sub.2    ______________________________________    Calculated m/z:                   201.1603    Found m/z:     201.1601    ______________________________________

Specific rotation α!D²⁰ +19.6° (c=1, CHCl₃)

The following compound was obtained in a similar manner.

(3S,4S)-3-(tert-Butoxycarbonyl)amino-4-ethylpyrrolidine

Appearance: pale yellow crystals

m.p.: 63.5°-65.5° C. IR spectrum ν(KBr) cm⁻¹ : 1712 NMR spectrumδ(CDCl₃) ppm: 0.94 (3H, t, J=7.5 Hz), 1.20-1.33 (1H, m), 1.39-1.51 (1H,m), 1.44 (9H, s), 1.98-2.08 (1H, m), 2.49-2.57 (1H, m), 2.75-2.81 (1H,m), 3.10-3.24 (2H, m), 4.09-4.20 (1H, m), 4.68-4.79 (1H, m) Specificrotation: α!_(D) ²⁰ +2.30 (c=1, CHCl₃)

5-Amino-7-(3S,4S)-3-tert-butoxycarbonylamino-4-methyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid

A mixture of 1.01 g of5-amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid-O³,O⁴ !difluoroborate, 0.71 g of(3S,4S)-3-tert-butoxycarbonylamino-4-methylpyrrolidine, 0.51 ml ofN,N-diisopropylethylamine, and 4.04 ml of dimethylsulfoxide was stirredat outer temperature of 30° C. for 64 hours. Water was added to thereaction mixture under ice cooling, and the mixture was extracted withmethylene chloride. The methylene chloride layer was washed successivelywith water and brine, and then dried and concentrated under reducedpressure. The resulting residue was purified by column chromatography(silica gel, methylene chloride: methanol=100:1), and crystals obtainedwere washed with diethyl ether to give 0.58 g of yellowish orangecrystals. A mixture of 0.58 g of the crystals obtained, 0.58 ml oftriethylamine, 11.6 ml of methanol, and 5.8 ml of 1,2-dichloroethane washeated under reflux for 3 hours. The reaction mixture was concentratedunder reduced pressure, and then, the residue was added with water andcrystals precipitated were collected by filtration. The crystals werewashed with water to give 0.52 g of yellow crystals. The crystals wererecrystallized from acetone-diisopropyl ether to give yellow crystals,m.p. 178.5°-180° C.

    ______________________________________    Analysis for C.sub.24 H.sub.31 FN.sub.4 O.sub.5    ______________________________________    Calculated %               C, 60.75     H, 6.58 N, 11.81    Found %    C, 60.59     H, 6.55 N, 11.73    ______________________________________

Specific rotation α!_(D) ²⁰ -141.9° (c=0.1, CHCl₃)

5-Amino-7-(3S,4S)-3-amino-4-methyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid

5-Amino-7-(3S,4S)-3-tert-butoxycarbonylamino-4-methyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid (0.45 g) was added with stirring to 0.77 ml of conc. hydrochloricacid under ice cooling, and after stirring was continued for 3 minutesat room temperature, 0.77 ml of water was added to the mixture andstirring was further continued at room temperature for 10 minutes. Themixture was adjusted to pH 11 with 10% aqueous sodium hydroxide, andthen to pH 8 with 10% hydrochloric acid and extracted with methylenechloride-methanol (9:1). The organic layer was washed with water andthen dried, and concentrated under reduced pressure to obtain yellowcrystals. The crystals were recrystallized from methylenechloride-diethyl ether to give 0.24 g of yellow crystals. The crystalswere recrystallized from ethanol-diethyl ether to give yellow crystals,m.p. 212.5°-213.5° C.

    ______________________________________    Analysis for C.sub.19 H.sub.23 FN.sub.4 O.sub.3.1/4H.sub.2 O    ______________________________________    Calculated %               C, 60.23     H, 6.25 N, 14.79    Found %    C, 60.32     H, 6.32 N, 14.47    ______________________________________

Specific rotation α!_(D) ²⁰ -159.8° (c=0.1, DMF)

5-Amino-7-(3S,4S-3-tert-butoxycarbonylamino-4-ethyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid

A mixture of 2.00 g of5-amino-1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid, 2.19 g of (3S,4S)-3-tert-butoxycarbonylamino-4-ethylpyrrolidine,0.95 ml of triethylamine, and 8 ml of dimethylsulfoxide was heated withstirring at inner temperature of 94°-102° C. for 87 hours. The reactionmixture was poured into 40 ml of ice-water, and then the crystalsprecipitated were collected by filtration and washed with water toobtain 3.41 g of yellowish brown crystals. The product was purified bycolumn chromatography (silica gel, methylene chloride:methanol=50:1) togive 2.01 g of yellow foamy product.

NMR spectrum δ(DMSO-d₆) ppm: 0.66-0.75 (1H, m), 0.80-0.85 (1H, m), 0.92(3H, t, J=7.5 Hz), 1.03-1.19 (2H, m), 1.30-1.55 (2H, m), 1.41 (9H, s),2.16-2.25 (1H, m), 2.32 (3H, s), 3.13-3.29 (1H, m), 3.41-3.52 (2H, m),3.83-3.93 (1H, m), 4.10-4.29 (2H, m), 6.93-7.10 (3H, m), 8.60 (1H, s)Specific rotation α!_(D) ²⁰ -213.1° (c=0.1, CHCl₃)

5-Amino-7-(3S,4S)-3-amino-4-ethyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid

Concentrated hydrochloric acid (2.9 ml) was stirred under ice cooling,and then added portionwise with 1.70 g of 5-amino-7-(3S,4S)-3-tert-butoxycarbonylamino-4-ethyl-1-pyrrolidinyl!-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid. The mixture was stirred at room temperature for 5 minutes, andthen added with 2.9 ml of water and stirring was further continued for10 minutes. The reaction mixture was added with 5 ml of methylenechloride and stirred, and then layers were separated and aqueous layerwas washed twice with methylene chloride. The aqueous layer was addedwith 10% aqueous sodium hydroxide to adjust its pH to above 11. Afterstirring was continued for 20 minutes, the mixture was adjusted to pH 8with 10% hydrochloric acid, and then crystals precipitated werecollected by filtration and washed with water to obtain 1.09 g of yellowcrystals. The crystals were recrystallized from methanol:water=4:1 togive 0.84 g of yellow crystals, m.p. 222.5°-224.5° C.

    ______________________________________    Analaysis for C.sub.20 H.sub.25 FN.sub.4 O.sub.3 ·5/4H.sub.2 O    Calculated % C, 58.45   H, 6.74   N, 13.63    Found %      C, 58.22   H, 6.52   N, 13.68    ______________________________________

Specific rotation α!_(D) ²⁰ -244.8° (c=0.1, 0.1N HCl)

Example 2 Test example

In the following test examples,5-amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid was used as the compound 1 of the present invention, and5-amino-7-((3S,4S)-3-amino-4-ethyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid as the compound 2 of the present invention. Ciprofloxacin (TheMerck Index 11th Edition, No.2315) was used as the reference compound A,and5-amino-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxo-7-piperazinylquinoline-3-carboxylicacid (the Japanese Patent Unexamined Publication (KOKAI) No.(Sho)62-215572/1987) as the reference compound B.

1. Antibacterial spectrum against standard strains and clinicallyisolated strains

Antibacterial activities (minimum inhibitory concentration: MIC) weredetermined according to the standard method of the Japan Society ofChemotherapy (Chemotherapy (Tokyo), 29 (1), 76, 1981) by using standardstrains and strains isolated from patients of infectious disease(clinically isolated strains) and applying 10⁶ viable cells per ml.Results are shown in Table 1-A and Table 1-B. The compound (I) of thepresent invention exhibited excellent antibacterial activities comparedto the reference compound A and B, especially against clinicallyisolated strains. Names of the bacteria are as follows:

Staphylococcus aureus (S. aureus)

Enterococcus faecalis (E. faecalis)

Escherichia coli (E. coli)

Klebsiella pneumoniae (K. pneumoniae)

Serratia marcescens (S. marcescens)

Enterobacter cloacae (E. cloacae)

Acinetobacter calcoaceticus (A. calcoaceticus)

                                      TABLE 1-A    __________________________________________________________________________    Antibacterial activities (standard strains, minimum inhibitory    concentrations, μ g/ml)    Bacteria    Compound                      Compound                            Reference                                    Reference    tested  Gram                1     2     Compound A                                    Compound B    __________________________________________________________________________    S. aureus            +   0.006 0.006 0.20    0.10    FDA 209P JC-1    E. coli --  0.006 0.012 0.025   0.05    NIHJ JC-2    K. pneumoniae            -   0.0008                      ≦0.0015                            0.012   0.006    PCI-602    S. marcescens            -   0.05  0.10  0.10    0.20    IAM 1184    E. colacae 963            -   0.012 0.025 0.05    0.10    __________________________________________________________________________

                                      TABLE 1-B    __________________________________________________________________________    Antibacterial activities (clinically isolated strains, minimum    inhibitory    concentrations, μg/ml)                   Compound                         Compound                               Reference                                      Reference    Bacteria tested                Gram                   1     2     Compound A                                      Compound B    __________________________________________________________________________    S. aureus HPC527                +  0.006 0.006 0.39   0.10    S. aureus HPC308                +  0.20  0.10  25     6.25    S. aureusHPC292                +  0.78  0.78  50     25    E. faecalis HPC984                +  0.05  0.05  0.39   0.39    E. faecalis HPC948                +  0.10  0.20  3.13   6.25    E. faecalis HPC975                +  0.78  0.78  50     12.5    E. cloacae HNR1939                -  0.10  0.20  0.78   0.78    E. cloacae HNR1946                -  0.10  0.20  0.78   0.78    E. cloacae HNR1941                -  3.13  6.25  25     25    A. calcoaceticus HNR916                -  0.006 0.012 0.39   0.10    A. calcoaceticus HNR939                -  0.20  0.20  6.25   3.13    A. calcoaceticus HNR904                -  1.56  3.13  100    50    K. pneumoniae HNR858                -  0.10  0.20  0.78   0.78    K. pneumoniae HNR869                -  0.78  1.56  3.13   6.25    K. pneumoniae HNR828                -  3.13  3.13  12.5   12.5    S. marcescens HNR1544                -  0.025 0.05  0.10   0.10    S. marcescens HNR1792                -  1.56  1.56  6.25   6.25    S. marcescens HNR1767                -  6.25  12.5  50     50    __________________________________________________________________________

2. Chromosomal aberration test

The experiments were carried out using a Chinese hamster lung cell line(CHL cell). The test compounds prepared were added to cultured cells,and cultivation was continued for 6 hours at 37° C. in 5% CO₂.2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide was used as a positivecontrol. After the cultivation for 6 hours, the cells were washed andadded with fresh medium, and then cultivation was further continued for18 hours. Colcemide solution was added to the culture 2 hours before thecompletion of the cultivation, and the chromosomal specimens wereprepared after the cultivation was completed. Incidence rates ofaberration cells were measured at the treatments with 100 μg/ml of thetest compounds. As a result, the incidence rate of the aberration cellswas less than 10% for each of the compound 1 of the present invention,the reference compound A, and the reference compound B.

3. Phototoxicity

Male Hartley guinea pigs were intravenously administered with testcompounds at a dose of 10 mg/kg, and then immediately exposed to WVA ontheir backs for 90 minutes. Erythemas on the UV irradiated skin wereobserved 24 hours after the irradiation. The number of guinea pigs witherythemas was shown in Table 2. The compound 1 of the present inventioninduced no phototoxicity, whereas phototoxicities were observed in morethan the half (three of five animals) as for the reference compound A.

4. The induction of convulsions

1) Intraperitoneal (i.p.) administration

Fasted five-week-old male ICR mice were orally administered withfenbufen at a dose of 100 mg/kg. After 30 minutes, the animals wereintraperitoneally administered with the test compound at a dose of 100mg/kg, and the absence or presence of induction of convulsions wasobserved. The number of mice with convulsions was shown in Table 2. Thecompound 1 of the present invention did not induce convulsions, whereasconvulsions were observed in the half of the animals as for thereference compound A. In addition, although inducing actions ofconvulsions were not noticeable as for the reference compound B, all ofthe animals exhibited sedative symptoms that were considered asprecursory symptoms of convulsions.

2) Intracerebroventricular (i.c.v.) administration

Male Wistar rats (weighing 180-220 g) were anesthetized with sodiumpentobarbital at 45 mg/kg, i.p., and then the head of the rat was fixedin a stereotaxic apparatus. A stainless steel guide cannula forintracerebroventricular injectionin in 0.6 mm diameter was implanted asa guide cannula so as to be positioned at 1.5 mm above the left lateralcerebroventricle (A:6.2,R:1.0,H:+1.0) according to the brain atlas of DeGroot (1959). The guide cannula was fixed by using a dental cement, andthen closed with a stainless steel stylet in 0.3 mm diameter. Potassiumpenicillin G (10,000 units) were subcutaneously administered to preventan infection. The rats were subjected to the experiments after recoverytime for several days from the surgery.

For the measurement of the induction of convulsions, 50 mg/kg offenbufen was intraperitoneally administered, and then the test compoundwas intracerebroventricularly administered after 30 minutes from theadministration of fenbufen by means of a stainless steel cannula in 0.3mm diameter that was connected with a polyethylene catheter and adjustedso as to be 1.5 mm longer than the guide cannula for an administrationat an accurate position of cerebroventricle (H:+1.0). Absence orpresence of appearance of convulsions was observed for at least 4 hours.After the completion of the above experiment, the administered positionswere confirmed by intraventricularly injecting 10 μl of 1% Evans blue toeach of the rats, and followed by sectioning the brains. The numbers ofrats with induction of convulsions were shown in Table 2. The compound 1of the present invention induced no convulsions, whereas convulsionswere observed in all of the animals (each three animals) as for thereference compound A and B.

(Reference)

De Groot, J. (1959). The rat forebrain in stereotaxic coordinates. Ver.Kon. Ned. Acad. Wet., Natuurkunde 52: 1-40

                  TABLE 2    ______________________________________    Photoxicity and induction of convulsions                       Induction of convulsion    Compound tested                 Photoxicity i.p.     i.c.v.    ______________________________________    Compound 1   0/5         0/6      0/6    Reference Compound A                 3/5         3/6      3/3    Reference Compound B                 0/5          0/6.sup.1)                                      3/3    ______________________________________     .sup.1) All of the animals exhibited sedative symptoms that were     considered as precursory symptoms of convulsions

INDUSTRIAL APPLICABILITY

The compounds (I) of the present invention have excellent antibacterialactivities, and induce no phototoxicity, chromosomal aberration, andinduction of convulsion, and thus they are useful as antibacterialagents. The compounds (II) of the present invention are useful forefficient preparations of the aforementioned compounds (I).

What is claimed is:
 1. A compound or a salt thereof represented by thefollowing formula (I): ##STR10## wherein asymmetric carbon atoms markedwith asterisks are in the S-configurations, and R¹ represents methylgroup or ethyl group. 2.5-Amino-7-((3S,4S)-3-amino-4-methyl-1-pyrrolidinyl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid or a salt thereof.
 3. A compound represented by the followingformula (II): ##STR11## wherein the asymmetric carbon atoms marked withasterisks are in the S-configurations; R¹ represents methyl group orethyl group; R² represents a hydrogen atom, a lower alkyl group, or BF₂group; and R³ and R⁴ independently represent a hydrogen atom or an aminoprotective group; with the proviso that R², R³, and R⁴ are notsimultaneously hydrogen atoms.
 4. A pharmaceutical compositioncomprising a compound or a pharmacologically acceptable salt thereofrepresented by the following formula (I): ##STR12## wherein asymmetriccarbon atoms marked with asterisks are in the S-configurations, and R¹represents methyl group or ethyl group.
 5. An antibacterial methodcomprising administering a compound or a pharmacologically acceptablesalt thereof represented by the following formula (I): ##STR13## whereinasymmetric carbon atoms marked with asterisks are in theS-configurations, and R¹ represents methyl group or ethyl group.
 6. Anorganic synthesis method comprising converting a compound represented bythe following formula (I), wherein asymmetric carbon atoms marked withasterisks are in the S-configurations, and R¹ represents methyl group orethyl group: ##STR14## into a compound represented by the followingformula (II): ##STR15## wherein asymmetric carbon atoms marked withasterisks are in the S-configurations; R¹ represents methyl group orethyl group; R² represents a hydrogen atom, a lower alkyl group, or aBF₂ group; and R³ and R⁴ independently represent a hydrogen atom or anamino protective group; with the proviso that R², R³, and R⁴ are notsimultaneously hydrogen atoms.